A technique of making a failure diagnosis while referring to a past failure instance has been known which is realized by collecting operation information of a device obtained from a sensor installed in the device and maintenance information indicating maintenance contents or the like (such as a failure name and a failure part) when the device has failed, in association with each other. In such a technique, if a maintenance operator makes an error in inputting the maintenance information, erroneous information is collected.
Techniques for preventing such an error are disclosed in, for example, Japanese Laid-Open Patent Application, Publication No. 2003-15877 (to be referred to as Patent Document 1 hereinafter) and Japanese Laid-Open Patent Application, Publication No. 2006-215682 (to be referred to as Patent Document 2 hereinafter). In the technique of Patent Document 1, a failure diagnosis of a device is performed based on inputted information concerning an operational status of the device, and, only if the diagnosis is successfully completed, an instance of interest is collected as a failure instance. In the technique of Patent Document 2, a maintenance operator inputs information concerning a device in failure in question-and-answer format in accordance with given guidance information, and the received information is accumulated to thereby gradually improve accuracy of the information concerning the device in failure.